Polyphenylene ethers have long been known as a widely used class of thermoplastic engineering resins characterized by excellent hydrolytic stability, dimensional stability, toughness, heat resistance and dielectric properties. Such polyphenylene ethers can be capped with epoxy materials, as for example, epoxy triazine. The capping procedures can result in products having higher workability, solvent resistance, and in some cases, improved other properties. Such capped polyphenylene ethers have been blended with modifying materials or used as modifying materials, as for example, with polyesters and with polyamides, to improve properties.
U.S. patent application Ser. No. 07/351,903, filed May 15, 1989, now U.S. Pat. No. 5,089,566 (corresponding to European Patent Application 347,828 published Dec. 27, 1989), describes advantageous polyphenylene ether/polyester co-polymers obtained from epoxytriazine capped polyphenylene ethers. U.S. patent application Ser. No. 07/351,905, filed May 15, 1989, now U.S. Pat. No. 5,096,979 corresponding to European Patent Application 347,827, published Dec. 27, 1989, describes epoxytriazine capped polyphenylene ethers and methods of preparation. U.S. patent application Ser. No. 07/534,573, filed Jun. 7, 1990, now U.S. Pat. No. 5,010,144 describes advantageous polyphenylene ether/polyester copolymers and polyphenylene ether/polyamide copolymers obtained from phosphatetriazine capped polyphenylene ethers. U.S. patent application Ser. No. 07/534,595, filed Jun. 7, 1990, now abandoned describes phosphatetriazine capped polyphenylene ethers and methods of preparation. These U.S. applications and their corresponding European patent applications, as published, describe materials which are treated by the method of this invention to obtain the products of this invention and each of these U.S. applications and their corresponding European Patent applications are incorporated by reference in total in this application.
As described in the patent applications incorporated by reference herein, chlorocyanurate derivatives have been shown to be highly efficient functionalization agents for polyphenylene ethers. Such materials are made by a reaction that utilizes an alkali metal hydroxide such as sodium hydroxide as a basic reagent, and alkali metal chlorides can be produced as by-products of the capping reaction. After the capping reaction is completed, the solution may be neutralized by addition of carbon dioxide. If neutralization of excess alkali metal hydroxide is employed, other salts, along with alkali metal chlorides can be produced, depending upon the exact stoichiometry employed in the capping reaction. For example, if sodium hydroxide is used as the base and carbon dioxide is added at the end of the capping reaction, sodium carbonate and sodium chloride could be anticipated to be present in the reaction mixture, depending on the exact stoichiometry employed in the reaction.
When ammonium containing materials or tertiary amines are present in capping reactions, excess ammonium ions can be left in the capped polyphenylene ethers produced.
It has now been found that the desirable properties of capped polyphenylene ethers can be improved by assuring a low level, or the absence of, alkali metal ions and ammonium ions in the resultant capped polyphenylene ethers, particularly when the ethers are combined with polyesters, polyamides or mixtures thereof. While the exact mechanism for the advantages obtained is not fully understood, it is believed that alkali metal ions and ammonium ions, and salts thereof, if present will attack polyesters and polyamides combined with the polyphenylene ethers to lower desirable properties and particulary notched Izod impact values thereof. Higher Izod impact values, as can be obtained by the use of the methods and products of this invention, are indicative of an increased robustness of the polymeric products obtained which are useful in a variety of conventional processing and molding steps.